Mechanical writing instruments of the propel-repel type comprise two inter-related tubes. One tube provided with the writing end is termed the body. The other tube removably secured to the body is termed, simply the top. The propel-repel mechanism may be located in the body or in the top. In either event, the lower end of the body tube is provided with the writing element which provides a closure member for the lower end of the body tube. The upper end of the body tube is normally left open and is constructed, so as to removably secure the top to the body.
The lower end of the top tube is open and adapted to cooperate with the open upper end of the body tube so as to be removably secured thereto.
There has always remained a problem of what to do with the open upper end of the top tube. In some instances the top end is swedged over to close the top.
The mechanical writing instrument is classed as an article of jewelry, especially when fabricated from precious metal such as sterling silver and gold-filled or gold-rolled tubes.
The top must therefore present an esthetic appearance to provide sales appeal and a price beyond that of a lead pencil.
Various types of plugs and configurations have been provided to close the top end of the top. Such plugs and configurations have then been used as symbols to indicate the source of manufacture and thereby have become trade marks.
As trade marks, the configurations have remained constant so as to represent the source of manufacture. In this manner, no consideration was given to the personality of the individual who ultimately purchased the article of jewelry for their personal use.